Packet-switched networks are being deployed by telecommunications providers to service the growing demand for data services in the corporate and consumer markets. The architecture of packet-switched networks such as Ethernet based networks is easy to deploy in smaller networks but not easily scalable in larger metropolitan area networks (MAN) or wide area networks (WAN) or provide the standards of service associated with service providers. Therefore Ethernet networking has traditionally been limited to Local Area Networks (LAN) deployments.
Use of Ethernet switches in carrier's networks has the advantages of interoperability (mappings between Ethernet and other frame/packet/cell data structures such as IP and ATM are well known) and economy (Ethernet switches are relatively inexpensive compared to IP routers, for example). However, the behavior of conventional switched Ethernet networks is incompatible with carriers' requirements for providing guaranteed services to customers and provide the ability to scale the network to a growing customer base. Carriers need networks to be meshed for load balancing and resiliency—i.e. there must be multiple paths across it. In addition any network must provide the ability to perform traffic engineering, i.e. the ability of the network operator to control the provisioning of explicitly routed variable bandwidth connections (or tunnels) through which traffic may be directed and to provide the ability to easily add network capacity as required.
Conventional Ethernet networking which was developed for the local area network (LAN) must be inexpensive and simply connected, i.e. there must be one and only one path between each and every node of the network. As a consequence, Ethernet does not have support for network-wide load balancing, suffer from resiliency problems, cannot support traffic engineering, and cannot be easily scaled for growth in larger network architectures.
To facilitate the deployment of Ethernet technologies standards have been evolving to address some of the growth and internetworking issues. In particular, standards such as 802.1ad, entitled Provider Bridges and 802.1ah entitled Provider Backbone Bridges have been developed by the Institute of Electrical and Electronics Engineers (IEEE) to help address some of the internetworking issues.
802.1ad defines an architecture and bridge protocols compatible and interoperable with existing Bridged LAN protocols and equipment and is also known as QinQ with VLAN stacking. Separate instances of MAC services to multiple independent users of a bridged LAN in a manner that does not require cooperation among the users is defined. 802.1ad requires a minimum of cooperation between the users and the provider of the MAC service and is referred to a Provider Bridge (PB). Virtual LAN identifiers (VID) are added to the Ethernet header (which is also known as stacking) to offer the equivalent of separate LAN segments, bridged or virtual bridged LANs, to a number of users, over the service provider's bridged network.
802.1ah defines an architecture and bridge protocols compatible and interoperable with Provider Bridged Network protocols and equipment allowing interconnection of multiple Provider Bridged Networks, to allow scaling and to support management including simple network management protocol (SNMP). This standard is also referred to as Provider Backbone Bridging (PBB) or MACinMAC addressing as source and destination Media Access Control (MAC) addresses are added to the Ethernet header to define sources and destination backbone MAC addresses. Each IEEE 802.1ah level encapsulates frames with a new MAC address and with a new service identifier (I-SID). Each IEEE 802.1ah nesting level summarizes the MAC addresses of the lower level with a backbone MAC address. The higher level 802.1ah bridges forward on summarized addresses allowing indefinite scaling without MAC lookup table explosion.
Other proposed architectural solutions for scaling Ethernet networks such as IEEE 802.Q entitled Virtual LANs have been developed. 802.1Q proposes that Local Area Networks (LANs) of all types may be connected together with Media Access Control (MAC) Bridges by defined a VID. This solution only provides 4094 services per VSI. Alternate solutions such as Virtual Private LAN Services (VPLS), which provides over a million unique identifiers, (Multi Protocol Label Switching (MPLS) Labels) but has resiliency issues, and requires manual coordination of flushing of MAC tables when an error occurs.
Accordingly, systems and methods that enable scalable and reliable carrier grade Ethernet network to be deployed in the carrier backbone remains highly desirable.